Deceptive interference may be defined as transmitted signals intended to subtly mislead a targeted satellite navigation receiver. These interfering signals may overwhelm the targeted receiver with counterfeit signals generated to induce a gradual drift error in position and time as the counterfeit signals are processed by the receiver. Encryption of signals may reduce susceptibility to deceptive interference for some (e.g., military) users while others (e.g., commercial) remain vulnerable to attack. Concern for this threat may increase with increasing sophistication of electronics available to the general public.
Deceptive interference may be a major concern for vulnerable systems including commercial and military Global Positioning System (GPS) users operating on unencrypted GPS signals. Moreover, users of open access Global Navigation Satellite System (GNSS) signals may be particularly vulnerable to deceptive interference of a positioning signal.
Several approaches based on a variety of discrimination methods have been proposed but have found limited success. Most have marginal effectiveness from limitations in capabilities and/or application. For example, an angle-of-arrival discrimination based on multi-antenna sensors may find limited success. However these systems require costly additional components such as a multi-element antenna and, on a moving platform, an inertial sensor to verify results.
With the advent of newer GNSS systems, interest in using unencrypted open service signals has grown. The extra layer of encryption may be cumbersome to many users since security key management may involve tedious protocols. Civil users may be dissuaded from encryption use by these additional complexities if there are less complex alternatives which offer the same degree of assurance against deceptive interference.
Consequently, a need exists for a system and method for effective autonomous signal authentication of a received positioning signal.